Definition

A QR Code is a matrix code (or two-dimensional bar code) created by Japanese corporation Denso-Wave in 1994. The "QR" is derived from "Quick Response", as the creator intended the code to allow its contents to be decoded at high speed.
QR Codes are common in Japan, where they are currently the most popular type of two dimensional codes. Moreover, most current Japanese & Nokia mobile phones phones can read this code with their camera.
QR Codes storing addresses and URLs may appear in magazines, on signs, buses, business cards or just about any object that users might need information about. Users with a camera phone equipped with the correct reader software can scan the image of the QR Code causing the phone's browser to launch and redirect to the programmed URL.
Source: http://en.wikipedia.org/wiki/QR_Code

About QR code
QR code for www.ecb.europa.eu
What is this image?
An image like this is called a “QR code”. It represents the web address (URL) of a single HTML page. The image shown on the left stands for “www.ecb.europa.eu”.

Mobile bookmarking
A QR code enables you to bookmark an ECB web page with your mobile phone quickly and easily. Our URLs can get very long: “www.ecb.europa.eu/paym/sepa/benefits/consumers/html/index.en.html” is one example. But with a QR code there is no need to type the full URL into your phone, instead you simply scan the image. Your phone reads it, converts it back into the URL and stores it as a bookmark. Then you can use your phone to go online to that page.
What you need
* A mobile phone with a camera
* A mobile phone with internet access if you want to go straight online
* A QR code reader installed on the phone
There may not be a QR code reader for some models of mobile phones.